Though the literature describes a specific set of perceptual characteristics of the speech of Parkinsonian individuals, including hoarseness, restricted pitch range and indistinct articulation, the specific factors responsible, in different parts of the articulatory system, are poorly understood. This research is designed to answer questions about three potential areas of abnormal function; (1) the pattern of laryngeal vibration may be abnormal, due to asymmetric tension and rigidity in the folds themselves, (2) rigidity and asymmetric tension in the circumlaryngeal structures may cause abnormal source-tract interactions and (3) upper articulator movements may be abnormal, due to bradykinesia and hypokinesia in the lips, tongue and jaw. Novel and well-tried techniques will be combined to address these possibilities in a population of moderate Parkinsonian subjects, whose primary symptom is rigidity, now being studied at Yale-New Haven Hospital. Appropriate comparisons will be made with normal individuals. High speed digital images of vocal fold vibration, using a computerized analysis technique, correlated with acoustic data, will be sued to evaluate fold asymmetry and opening and closing patterns, in normal and hydrated conditions. The role of asymmetry and failure of normal reciprocity will be evaluated more directly by electromyographic studies of cricothyroid, thyroarytenoid and posterior cricoarytenoid muscles, using techniques developed at Haskins. Observations of circumlaryngeal structural relations will be made using Magnetic Resonance imaging. Upper articulatory events will be monitored aerodynamically by pressure transducers and a newly developed magnetometer system, or by more conventional Selspot technology. By studying a small group of patients by multiple techniques, we should gain a better understanding of the articulatory origins of the speech symptoms observed in this population. This understanding may, in turn, lead to more efficient management.